Rechercher une fonction PHP

Limitations

Contents

There are the following limitations in the current release of the Relational DAS:

  • No support for nulls. There is no support for SQL NULL type. It is not legal to assign PHP NULL to a data object property and the Relational DAS will not write that back as a NULL to the database. If nulls are found in the database on a query, the property will remain unset.

  • Only two types of SDO relationship. The metadata described below allows the Relational DAS to model just two types of SDO relationship: multi-valued containment relationships and single-valued non-containment references. In SDO, whether a property describes a single- or multi-valued relationship, and whether it is containment or non-containment, are independent. The full range of possibilities that SDO allows cannot all be defined. There may be relationships that it would be useful to model but which the current implementation cannot manage. One example is a single-valued containment relationship.

  • No support for the full range of SDO data types. The Relational DAS defines all primitive properties in the SDO model as being of type string. SDO defines a richer set of types containing various integer, float, boolean and data and time types. String is adequate for the purposes of the Relational DAS since the combination of PHP, PDO and the database will ensure that values passed as strings will be converted to the proper type before being put in the database. This does affect some scenarios in which the Relational DAS has to work with a data graph that has come from or will go to a different DAS.

  • Only one foreign key per table. The metadata only provides the means to specify one foreign key per table. This foreign key may be mapped to one of the two types of SDO relationship supported. Obviously there are some scenarios that cannot be described under this limitation - it is not possible to have two non-containment references from one table to another for example.

Find a PHP function

English translation

You have asked to visit this site in English. For now, only the interface is translated, but not all the content yet.

If you want to help me in translations, your contribution is welcome. All you need to do is register on the site, and send me a message asking me to add you to the group of translators, which will give you the opportunity to translate the pages you want. A link at the bottom of each translated page indicates that you are the translator, and has a link to your profile.

Thank you in advance.

Document created the 30/01/2003, last modified the 26/10/2018
Source of the printed document:https://www.gaudry.be/en/php-rf-sdodasrel.limitations.html

The infobrol is a personal site whose content is my sole responsibility. The text is available under CreativeCommons license (BY-NC-SA). More info on the terms of use and the author.

References

  1. View the html document Language of the document:fr Manuel PHP : http://php.net

These references and links indicate documents consulted during the writing of this page, or which may provide additional information, but the authors of these sources can not be held responsible for the content of this page.
The author This site is solely responsible for the way in which the various concepts, and the freedoms that are taken with the reference works, are presented here. Remember that you must cross multiple source information to reduce the risk of errors.

Contents Haut